Gas exchange

Pneumoconiosis is a lung disease caused by breathing in coal dust particles. The X-ray shows the lungs of a person with pneumoconiosis.

Coal dust particles collect in the alveoli and cannot be removed. Cells grow around these coal dust particles, forming tissue that traps the particles.

State what is meant by the term tissue.

Suggest why pneumoconiosis reduces the ability of a person to exercise.

In the UK, in 2013, breathing in dust particles resulted in diseases that caused 260 000 deaths. The graph shows the number of these deaths caused by breathing in dust particles of asbestos, coal and silica.

Calculate the number of deaths in the UK, in 2013, caused by breathing in dust particles other than asbestos, coal or silica.

number of deaths =_........

Give two conclusions that can be made from the data in the graph.

7 (a) The table lists descriptions of what happens in different human organs. Complete the table by giving the correct organ for each description. The first one has been done for you.

Describe the structure of the kidney. Refer to the structure of the nephron in your answer.

The diagram shows part of a cross-section of a plant leaf.

Describe the function of layer A.

Name the cells labelled B, C and D.

Explain the role of cell D in controlling gas exchange in the leaf.

Describe the function of the tissue labelled E.

Human lungs and plant leaves both contain gas exchange surfaces. These gas exchange surfaces have a number of features in common.

The diagram shows a cross-section through human lung tissue.

Explain, with reference to features shown in the diagram, how lung tissue enables efficient gas exchange.

Explain how the structure of a leaf is adapted for efficient gas exchange.

The diagram shows a cross section through a leaf.

Each part of the leaf is adapted for a specific function. Name each part of the leaf and explain how it helps the leaf in photosynthesis.

Layer A

Layer B

Layer C

Structure D

Water lilies float on the surface of ponds. Structure D is found on the upper surface of a water lily rather than the lower surface. Suggest a reason for this adaptation.

A student examined the upper and lower surfaces of a leaf from a land plant using a microscope. This is her diagram of the lower surface.

How many stomata are shown in the diagram?

Suggest how the upper surface of the land plant would differ from this diagram.

The graph shows the effect of increasing light intensity on the exchange of carbon dioxide in a green plant.

Describe the effect of increasing light intensity on the exchange of carbon dioxide.

Explain why there is no net exchange of carbon dioxide at point A.

Describe how you could use an indicator to show how the exchange of carbon dioxide by a leaf changes in the dark and in the light.

Fish breathe by opening their mouths to allow water containing oxygen to pass over their gills. This is shown in the diagram.

Gas exchange takes place in the gills. What is meant by the term gas exchange?

Fish use their gills as a gas exchange surface. Suggest three ways in which fish gills are adapted for efficient gas exchange.

Students investigated the effect of temperature on the breathing rate of fish. They put fish of the same size in tanks of water at different temperatures. They measured the breathing rate by counting the number of times the fish opened their mouths in a minute. The results are shown in the table.

Plot a line graph to show the effect of water temperature on the average breathing rate of the fish. Join the points with straight lines.

Suggest how the results support the hypothesis that warm water contains less oxygen than cold water.

The students controlled the size of fish. Explain why this is needed to make it a valid investigation.

Give two other factors the students should have controlled.

The diagrams show sections through an artery and a vein.

Use the information in the diagrams and your own knowledge to give three ways in which the structure of an artery differs from the structure of a vein.

Lack of movement by sitting still for long periods of time makes blood flow very slowly in a vein. Blood that flows slowly is more likely to clot than blood that flows normally. This problem is known as deep vein thrombosis (DVT). In DVT, the clot usually occurs in a leg vein as shown in the diagram.

DVT is dangerous because sometimes part of the clot breaks off and travels to the lung, blocking small blood vessels and causing death.

Suggest why blood flow in a leg vein is slow when there is lack of movement.

Name the blood cells responsible for transporting oxygen.

Suggest why a clot that blocks the small blood vessels in the lungs can cause death.

Caroline investigated how light affected photosynthesis by looking at changes in carbon dioxide levels. She placed 2 cm³ of orange hydrogen carbonate indicator solution into three test tubes. She put a leaf in two of the test tubes, which were then firmly sealed with a bung. These leaves were similar in size and were taken from the same plant. She wrapped one of the test tubes in foil to prevent light entering. The third test tube was firmly sealed with a bung but was without a leaf. She left the three test tubes in the conditions shown in the diagram for two hours. They were then shaken gently and the leaves were removed.

Hydrogen carbonate indicator solution is orange in normal air. It changes colour to red as the carbon dioxide level decreases. It changes to yellow as the carbon dioxide level increases. The colour of the indicator solution in each test tube was recorded. Her results are shown in the table.

C orange red

Explain the colour change observed in test tube C.

Explain the purpose of test tube B.

Caroline set up a fourth test tube that contained a leaf and was exposed to dim light. After two hours the colour of the indicator solution in this test tube remained orange. Explain why.

Caroline carried out another experiment to investigate the effect that light intensity has on the rate of photosynthesis in a water plant.

Suggest how she could change her independent variable.

Suggest how she could measure her dependent variable.

Suggest how she could ensure that her results were reliable.